There is a connect item for this located here. Please vote! The connect item states that it is related to AlwaysOn. This is not true. This bug occurs on any restart of the sql service.

A work-around for this is to make sure to checkpoint the database before a restart, but obviously it’s not the best work-around as you don’t always control the failover (HA). All that being said, if you checkpoint before a restart, you’ll not see the identity bug: